City Fire Chief James Clack said Thursday that the cause of the fatal fire was combustible materials stored against the home's furnace.

Crews were called to a house in the 5600 block of Denwood Avenue around 2 a.m. Oct. 12, where they found four children ranging in age from 1 to 7 and 55-year-old Nancy Worrell dead in a bedroom on the home's second floor.

Clack said five other people escaped the fire. Worrell's husband was seriously injured after family members said he jumped from the second floor to safety. Two firefighters were also injured fighting the blaze.

Fire officials said family members told them at the time that there were smoke detectors in the home, but officials said a preliminary investigation showed that didn't appear to be true.

Fire officials plan to release more details about the investigation on Thursday.

Photos: Fatal fire ravages Baltimore home

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Baltimore City Fire Department

Baltimore firefighters are called to a fatal fire on Denwood Avenue in northeast Baltimore.